The present invention relates to a heat treating method and a heat treating apparatus.
In the manufacture of a semiconductor device or a liquid crystal device, the nonuniformity in the temperature of resist or a base substrate in heating or cooling a target substrate to be processed is reflected on the nonuniformity in the size of the pattern. Thus, with miniaturization of the pattern, the temperature control of a higher precision is required.
For example, in a post exposure baking (PEB), which is one of the manufacturing steps of a photomask, the uniformity of the temperature within a plane of a photo mask blank is very important. It was customary in the past to employ a heating method using a heater in the PEB.
However, the following problem is generated in the heater heating system. Specifically, in the normal state, a good temperature uniformity is exhibited within a plane of a photo mask blank. However, in the transition period during which the photo mask blank is being heated, a temperature distribution is derived within a plane of the photo mask blank from the low heat conductivity and the large heat capacity of the quartz substrate, giving rise to a problem that the uniformity in the pattern size within the plane of the photo mask blank is made poor.
In view of the problem noted above, a lamp heating system is being studied. However, the following problem is generated in the case of the conventional lamp heating system. Specifically, in the lamp heating system, the uniformity of illuminance is poor within a lamp irradiating region, giving rise to a temperature drop in the boundary region between adjacent lamp irradiating regions. As a result, a temperature distribution is generated in the photo resist.
Also, in the lamp heating system, it is possible to heat selectively a target thin film to be heated such as resist or a light shielding film by selecting appropriately the wavelength of the light emitted from the lamp. However, since the target thin film is heated selectively, a large temperature difference is generated between the target thin film and the quartz substrate, making it difficult to perform the temperature control with a high accuracy.